1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a magnetic resonance imaging (MRI) apparatus and an MRI method.
2. Description of the Related Art
An MRI apparatus uses a magnetic field to capture an image of a subject, and is widely used in the accurate diagnosis of diseases because it shows stereoscopic images of bones, lumbar discs, joints, and nerve ligaments at desired angles. The MRI apparatus is configured to acquire MR signals and reconstruct the acquired MR signals into an image to be output. Specifically, the MRI apparatus acquires MR signals by using radio frequency (RF) coils, a permanent magnet, and gradient coils.
When an MR signal is acquired, unmeasured signals may be generated at junctions between RF coils. Furthermore, errors may occur when acquiring an MR signal. Due to the presence of unmeasured signals and errors in signal acquisition, artifacts or noise may occur in reconstructing a final MR image. The artifacts or noise present in an MR image may degrade the quality of the MR image. Thus, various techniques are being developed to remove artifacts or noise in an MR image. Examples of the techniques may include the use of a filter, a specialized recovery method to remove Gibbs ringing effects (e.g., a Gegenbauer reconstruction algorithm), and the like.
In detail, according to the filtering method, ringing artifacts may be mitigated by reducing high frequency components using a low-pass filter in the frequency domain. The specialized recovery method may include a Gegenbauer reconstruction algorithm that uses the sum of non-periodic segments of a Fourier series.
However, the filtering method using a low-pass filter has a drawback in that high frequency signal components of the original image are also removed when filtering the entire image signal. Thus, the use of a low-pass filter may result in the deterioration of the original image. In other words, if a low-pass filter is used to remove ringing artifacts, an edge of an image may be blurred, and a detail of the image containing critical information may become unclear.
As another approach for reducing ringing artifacts, a Gegenbauer reconstruction algorithm is extremely complicated, and requires long reconstruction time due to iterative computations. The algorithm has another drawback in that a detail of a generated MR image may not clearly represent an object being analyzed.